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Message-ID: <d9b092cde0f42bc6a8a1cb36ffee3478c46a3599.1754292567.git.leon@kernel.org>
Date: Mon, 4 Aug 2025 15:42:49 +0300
From: Leon Romanovsky <leon@...nel.org>
To: Marek Szyprowski <m.szyprowski@...sung.com>
Cc: Leon Romanovsky <leonro@...dia.com>,
Jason Gunthorpe <jgg@...dia.com>,
Abdiel Janulgue <abdiel.janulgue@...il.com>,
Alexander Potapenko <glider@...gle.com>,
Alex Gaynor <alex.gaynor@...il.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Christoph Hellwig <hch@....de>,
Danilo Krummrich <dakr@...nel.org>,
iommu@...ts.linux.dev,
Jason Wang <jasowang@...hat.com>,
Jens Axboe <axboe@...nel.dk>,
Joerg Roedel <joro@...tes.org>,
Jonathan Corbet <corbet@....net>,
Juergen Gross <jgross@...e.com>,
kasan-dev@...glegroups.com,
Keith Busch <kbusch@...nel.org>,
linux-block@...r.kernel.org,
linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org,
linux-mm@...ck.org,
linux-nvme@...ts.infradead.org,
linuxppc-dev@...ts.ozlabs.org,
linux-trace-kernel@...r.kernel.org,
Madhavan Srinivasan <maddy@...ux.ibm.com>,
Masami Hiramatsu <mhiramat@...nel.org>,
Michael Ellerman <mpe@...erman.id.au>,
"Michael S. Tsirkin" <mst@...hat.com>,
Miguel Ojeda <ojeda@...nel.org>,
Robin Murphy <robin.murphy@....com>,
rust-for-linux@...r.kernel.org,
Sagi Grimberg <sagi@...mberg.me>,
Stefano Stabellini <sstabellini@...nel.org>,
Steven Rostedt <rostedt@...dmis.org>,
virtualization@...ts.linux.dev,
Will Deacon <will@...nel.org>,
xen-devel@...ts.xenproject.org
Subject: [PATCH v1 15/16] block-dma: properly take MMIO path
From: Leon Romanovsky <leonro@...dia.com>
Make sure that CPU is not synced and IOMMU is configured to take
MMIO path by providing newly introduced DMA_ATTR_MMIO attribute.
Signed-off-by: Leon Romanovsky <leonro@...dia.com>
---
block/blk-mq-dma.c | 13 +++++++++++--
include/linux/blk-mq-dma.h | 6 +++++-
include/linux/blk_types.h | 2 ++
3 files changed, 18 insertions(+), 3 deletions(-)
diff --git a/block/blk-mq-dma.c b/block/blk-mq-dma.c
index 37e2142be4f7d..d415088ed9fd2 100644
--- a/block/blk-mq-dma.c
+++ b/block/blk-mq-dma.c
@@ -87,8 +87,13 @@ static bool blk_dma_map_bus(struct blk_dma_iter *iter, struct phys_vec *vec)
static bool blk_dma_map_direct(struct request *req, struct device *dma_dev,
struct blk_dma_iter *iter, struct phys_vec *vec)
{
+ unsigned int attrs = 0;
+
+ if (req->cmd_flags & REQ_MMIO)
+ attrs = DMA_ATTR_MMIO;
+
iter->addr = dma_map_phys(dma_dev, vec->paddr, vec->len,
- rq_dma_dir(req), 0);
+ rq_dma_dir(req), attrs);
if (dma_mapping_error(dma_dev, iter->addr)) {
iter->status = BLK_STS_RESOURCE;
return false;
@@ -103,14 +108,17 @@ static bool blk_rq_dma_map_iova(struct request *req, struct device *dma_dev,
{
enum dma_data_direction dir = rq_dma_dir(req);
unsigned int mapped = 0;
+ unsigned int attrs = 0;
int error;
iter->addr = state->addr;
iter->len = dma_iova_size(state);
+ if (req->cmd_flags & REQ_MMIO)
+ attrs = DMA_ATTR_MMIO;
do {
error = dma_iova_link(dma_dev, state, vec->paddr, mapped,
- vec->len, dir, 0);
+ vec->len, dir, attrs);
if (error)
break;
mapped += vec->len;
@@ -176,6 +184,7 @@ bool blk_rq_dma_map_iter_start(struct request *req, struct device *dma_dev,
* same as non-P2P transfers below and during unmap.
*/
req->cmd_flags &= ~REQ_P2PDMA;
+ req->cmd_flags |= REQ_MMIO;
break;
default:
iter->status = BLK_STS_INVAL;
diff --git a/include/linux/blk-mq-dma.h b/include/linux/blk-mq-dma.h
index c26a01aeae006..6c55f5e585116 100644
--- a/include/linux/blk-mq-dma.h
+++ b/include/linux/blk-mq-dma.h
@@ -48,12 +48,16 @@ static inline bool blk_rq_dma_map_coalesce(struct dma_iova_state *state)
static inline bool blk_rq_dma_unmap(struct request *req, struct device *dma_dev,
struct dma_iova_state *state, size_t mapped_len)
{
+ unsigned int attrs = 0;
+
if (req->cmd_flags & REQ_P2PDMA)
return true;
if (dma_use_iova(state)) {
+ if (req->cmd_flags & REQ_MMIO)
+ attrs = DMA_ATTR_MMIO;
dma_iova_destroy(dma_dev, state, mapped_len, rq_dma_dir(req),
- 0);
+ attrs);
return true;
}
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 09b99d52fd365..283058bcb5b14 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -387,6 +387,7 @@ enum req_flag_bits {
__REQ_FS_PRIVATE, /* for file system (submitter) use */
__REQ_ATOMIC, /* for atomic write operations */
__REQ_P2PDMA, /* contains P2P DMA pages */
+ __REQ_MMIO, /* contains MMIO memory */
/*
* Command specific flags, keep last:
*/
@@ -420,6 +421,7 @@ enum req_flag_bits {
#define REQ_FS_PRIVATE (__force blk_opf_t)(1ULL << __REQ_FS_PRIVATE)
#define REQ_ATOMIC (__force blk_opf_t)(1ULL << __REQ_ATOMIC)
#define REQ_P2PDMA (__force blk_opf_t)(1ULL << __REQ_P2PDMA)
+#define REQ_MMIO (__force blk_opf_t)(1ULL << __REQ_MMIO)
#define REQ_NOUNMAP (__force blk_opf_t)(1ULL << __REQ_NOUNMAP)
--
2.50.1
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